2005 Envoy - Switched 12-Volt Outlets?

Is there any way to program the 2005 Envoy so that the three 12-volt outlets switch off with the ignition?

I have several things plugged in, including radar detector and iTrip for my iPod, and Sirius receiver, and these things stay on all the time.

I know with my previous vehicles there was a simple fix to make them switched or fixed. Not sure how to do it though, so I'm asking you experts!